Method and system to send SMS messages in a hybrid network

ABSTRACT

Embodiments of a method and system are disclosed to pass SMS messages from a mobile operating in a CDMA Radio Access Network to a Hybrid MSC, and to route the SMS message from the Hybrid MSC to a GSM SMS-C in the Core network, the hybrid wireless network having at least one radio access network (RAN) based on CDMA technology and a core network (CN) based on GSM technology.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S.provisional patent application Ser. No. 60/342,780, filed on Dec. 21,2001, entitled “Method and System oo Send GSM SMS Message Over CDMARadio Network to a GSM Destination SMS Service Centre in the CoreNetwork.”

BACKGROUND OF THE INVENTION

The present disclosure relates generally data communications, and moreparticularly, to a system and method for providing Short Message Service(SMS) to a wireless mobile terminal operating in a hybrid wirelessnetwork.

A typical wireless network is composed of two sub-networks: a RadioAccess Network (RAN) which handles radio related issues such asassigning radio resources to a mobile terminal (or “mobile” in short)upon request for services, and a Core Network (CN) which links themobile user to wireline networks. Current specifications of wirelessnetworks require that the RAN and CN have the same wireless technologyin order to provide wireless services. These networks may be referred toas “homogeneous networks.” For instance, a GSM mobile will only operatein a wireless network which its RAN and CN are both GSM wirelesstechnology based. FIG. 1 illustrates a GSM wireless network 100 composedof a GSM RAN 102 and a GSM CN 104.

The GSM RAN 102 includes a GSM Mobile Station (MS) 106 that communicatesto a GSM Base Station System (BSS) 108 through a GSM radio channel 110.The GSM BSS 108 includes a GSM Base Transceiver Station (BTS) 110 andGSM Base Station Controller (BSC) 112.

The GSM Core Network (CN) 104 includes a GSM Mobile Switching Center(MSC) 120 that is connected to the GSM BSC 112 as well as a GSM GatewayMSC (GMSC) 122 by using SS7 ISUP communications 124. The GSM GMSC 122 isalso connected to the Public Switched Telephone Network (PSTN) 126 byusing SS7 ISUP communications 124. In this figure, a telephone 128 isshown to be connected to the PSTN 126 as an illustration of acalling/called party. In addition, a Serving General Packet RadioService Node (GPRS) (SGSN) 130 is shown to also be connected to the GSMBSC 112. Moreover, a GSM Short Message Service Center (SMS-C) 132, a GSMHome Location Register (HLR) 134 and a GSM Authentication Center (AuC)136 are all shown to be connected the GSM MSC 120 and the SGSN 130.Further, a GSM Service Control Point (SCP) 138 connects a GSM BillingSystem 140 to the GSM MSC 120 and the GSM HLR 134. The connection fromthe GSM Billing System 140 and the GSM MSC 120 utilizes IP.Additionally, a Packet Data Network (PDN) 142 is shown connected to theGSM CN 104 through a Gateway GPRS Node (GGSN) 144 utilizing IPcommunications.

A disadvantage of the homogeneous network is that, given many wirelesstechnologies that exist today and considering new ones being defined forthe future, this is a serious limitation in the wireless serviceprovision to deal with a situation in which a mobile compatible with onewireless technology moves into a wireless network of differenttechnology. This prevents the mobile from getting services and limitsthe mobile's geographical service area to networks that support aspecific wireless technology. The same limitation applies to wirelessnetworks that are CDMA wireless technology based. FIG. 2 illustratessuch a CDMA based network 200.

Turning to FIG. 2, a CDMA RAN 201 includes a CDMA MS 202 connected to aCDMA BSS 204 through a CDMA BTS 206. The CDMA BTS 206 is in turnconnected to a CDMA BSC 208, which connects to a Packet Control Function(PCF) 210. A CDMA CN 212 connects to the CDMA RAN 201 by the CDMA BSC208 connecting to a CDMA200 MSC 214. The CDMA MSC 214 is connected to anIS-41 SMS-C 216, an IS-41 HLR 218, an IS-41 AuC 220 and an IS-41 SCP222. The IS-41 SCP 222 in turn is also connected to the IS-41 HLR 218and a Store and Forward Service 224, which in turn is connected to anIS-41 Billing System 226. In addition, a Packet Data Serving Node (PDSN)228 is connected to the PCF 210 of the CDMA RAN 200 and a PDN 230.Moreover, the CDMA MSC 214 connects the CDMA CN 212 to a PSTN 232 and,for illustrative purposes, a phone 234.

A hybrid wireless network is a wireless network composed of a RAN and aCN of different technologies linked. Although hybrid wireless networkshave advantages, one difficulty is to enable the mobile terminal in theRAN and certain network entities in the CN to exchange message contentswithout being obstructed by the differences in the technologies involved(e.g., message encoding and decoding schemes). For instance, considerthe short message service (SMS) in a GSM Network. When a GSM handsetsends a Mobile Originated (MO) short message to the GSM MSC, the messagecontains not only the destination address but also the address of theSMS-C or Short Message Service Center. In GSM networks, each GSMsubscriber may have different address of the SMS-C because the addressof the SMS-C is stored in the GSM subscriber's SIM card. In contrast, aCDMA network typically uses a centralized SMS service centre to delivershort message. Consequently, the CDMA handset sends only the destinationaddress for the MO short message. Thus, in the CDMA protocol between theCDMA handset and the MSC, the service centre address is notcommunicated.

If a hybrid network system were created where a GSM SIM card could beinserted into the CDMA handset, a MO short message could be sent fromthe CDMA mobile handset to a hybrid MSC. However, the standard CDMAprotocol is still used between the CDMA handset and the Hybrid MSC.Under the standard CDMA protocol the GSM service centre address wouldnot be sent to the Hybrid MSC. What is needed, therefore, is a methodand system for providing sending SMS messages from the mobile to ahybrid MSC in a hybrid system and a routing mechanism in the hybrid MSCto route the SMS message to the appropriate SMS-C in the core network.

SUMMARY OF THE INVENTION

Embodiments of a method and system are disclosed to pass SMS messagesfrom a mobile operating in a CDMA RAN to a Hybrid MSC, and to route theSMS message from the Hybrid MSC to a GSM SMS-C in the Core network,where the hybrid wireless network having at least one radio accessnetwork (RAN) based on CDMA technology and a core network (CN) based onGSM technology.

When the mobile has an SMS message ready for transmission, the messageis first encoded based on the GSM SMS encoding scheme, then it isinserted in a CDMA message so that it can be sent on the CDMA radionetwork transparently. The destination address of the message is alsoencoded by the mobile before sending the message. The destinationaddress includes an embedded address that will be used by the Hybrid MSCto route the message to the appropriate SMS-C. In one embodiment, ADSSmessage type is used on the CDMA RAN to transfer the SMS message to theHybrid MSC.

Once the message reaches the Hybrid MSC, the latter will remove all CDMArelated headers and extract the embedded destination address. The HybridMSC then routes the SMS message to the appropriate GSM SMS-C in the Corenetwork using the embedded address. The remaining of the process followsthe same procedures used in existing SMS-C in GSM CNs.

In the illustrative embodiments, no modifications need to be introducedto the GSM core network specifications, creating advantages for networkoperators that are looking to expand their wireless service coverage ofa new radio technology. Also, the present disclosure needs very low costand short deployment time because that the core network does not have tobe modified.

The disclosed embodiments modify the CDMA SMS protocol so that the CDMAhandset can send the GSM SMS-C address as well as the destinationaddress to the GSM MSC. However, the modification is transparent to theBase Station System (BSS) and therefore no change at the BSS isrequired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a GSM wireless network architecture for providingservices to a mobile terminal.

FIG. 2 illustrates a CDMA wireless network architecture for providingservices to a mobile terminal.

FIG. 3 illustrates a hybrid wireless network architecture with a HybridMobile Switching Center and utilizing the CDMA wireless technology inthe RAN and GSM wireless technology in the CN according to one exampleof the present disclosure.

FIG. 4 illustrates an example call flow for SMS delivery solution

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of the present disclosure, various acronyms are used,and the definitions of which are listed below:

BSC Base Station Centre BSS Base Station System BTS Base stationTransceiver System CN Core Network GGSN Gateway GPRS Support Node—awireless gateway that allows mobile cell phone users to access thepublic data network (PDN) or specified private IP networks. GMSC GatewayMSC GPRS General Packet Radio Services GSM Global System for Mobilecommunications HLR Home Location Register IP Internet Protocol IS41Wireless Network conforming to the IS41 standard ISDN IntegratedServices Digital Network ISUP ISDN User Part (of SS7) MO MobileOriginated MSC Mobile Switching Centre PSTN Public Switch TelephoneNetwork RAN Radio Access Network SIM Subscriber Identity Module SGSNServing GPRS Support Node—sends data to and receives data from mobilestations, and maintains information about the location of a mobilestation. The SGSN communicates between the MS and the GGSN. SMS ShortMessage Service—a means by which short text messages can be sent overthe air from base stations to pagers, cell phones, or other handhelddevices. Alpha-numeric messages up to 160 characters are supported.SMS-C Short Message Service Center—the entity that stores and forwardsShort Message Service (“SMS”) messages.

The present disclosure provides several examples below, and it isunderstood that the examples are not necessarily limitations to thepresent disclosure, but are used to describe embodiments of the methodand system of the present disclosure.

FIG. 3 illustrates an example hybrid wireless network 300 which could beused to implement one aspect of the present invention. The wirelessnetwork 300 includes a GSM CN 302, which may be in communication with aGSM RAN 304 and/or a CDMA RAN 306. The RAN 304 and 306 communicate withthe CN 302 through a Hybrid Mobile Switching Center (HMSC) 308. In thisexample, the HMSC 308 has a centralized call control model for voice andpacket data calls. This module allows the HMSC 308 to handle and keeptrack of all calls for a given mobile phone. In contrast, in atraditional GSM MSC or a CDMA MSC the call control for data and voiceare located in different network entities. In this example embodiment,setting-up and controlling a voice or a data call for a mobile user isperformed at the HMSC 308.

The illustrative network 300 may provide both voice and packet dataservices to mobile stations in either of the two networks. For instance,in the GSM RAN 304, a GSM mobile unit 310 communicates with a GSM BTS312 over a GSM radio link 314. In this illustrative embodiment, the GSMmobile unit 310 is a dual mode GSM/CDMA unit having a SIM card (notshown). The GSM BTS 312 typically communicates with a GSM BSC 316 usinga wired link 318. The BTS 312 and BSC 316 comprise a base station systemor BSS 317. In the illustrative embodiments, the HMSC 308 communicateswith the GSM BSC 316 over a voice link 315 using an SS7 ISUP protocoland over a data link 319 using a Gb protocol.

Similarly, in the CDMA RAN 306, a CDMA 2000 mobile phone 320communicates with a CDMA BTS 322 over a CDMA radio link 324. The CDMABTS 322 typically communicates with a CDMA BSC 326 using a proprietarywired link 328. Typically, for voice communications, the CDMA BSC 326communicates with the HMSC 308 over a link 330 using a variety ofprotocols, including A1, A2, A5, A8, and A9. The CDMA BSC 326 transfersdata to a PCF 332 over a link 334 using A8 and A9 protocols. Thus, datais usually sent by the PCF 332 to the HMSC 308 over a link 336 using theA10 and A11 protocols.

If the core network is a GSM network, as in the illustrative network300, the HMSC 308 communicates with the other GSM network components inmuch the same way a typical MSC would communicate with the GSM networkcomponents. For instance, the HMSC 308 may establish links with a GMSC340, a SCP 342, an HLR 344, a AuC 346, a PDN 347, a GGSN 348, and/or aSMS-C 350. Similarly, the GMSC 340 may communicate with a PSTN 352through a T1 link 354 using a SS7 ISUP protocol as previously describedin reference to FIG. 2. Additionally, the SCP 342 may establish a link356 with a billing system 358, and the GGSN 348 may establish a link 360with the PDN 347, where the links 356 and 360 uses an IP protocol. Thus,for each connection, FIG. 3 illustrates an example link and thecorresponding communication protocol used to allow communication betweentypical network entities. As those skilled in the art would recognize,similar communication links may be established if the CN 302 were a CDMAnetwork.

Thus, for calls established with the GSM mobile 310, the HMSC 308 actslike a GSM MSC 110 as depicted in FIG. 1. For calls established with theCMDA mobile 320, the HMSC 308 links the CDMA RAN 304 to the GSM CN 302by translating and mapping CDMA RAN messages initiated in the RAN 304into GSM CN messages sent to the CN 302, and GSM messages initiated bythe CN 302 into CDMA messages sent to the RAN 306.

The HMSC 308 may support voice and packet data call services frommobiles in any type of RAN to any other type of network. For instancethe mobile 310 in the GSM RAN 304 can make a call to another mobile (notshown) operating in the CDMA RAN 306, a telephone 362 connected to thePSTN 352, or an entity as part of the PDN 347 and other networks thatare not illustrated nor discussed in this disclosure for reasons ofsimplicity and clarity. The HMSC 308 is shown in communication with twoRANs of different technologies, however as would be clear to one skilledin the art, the present invention also applies in situations where theHMSC 308 is in communication with one or more RANs of same technology.

FIG. 4 illustrates a SMS delivery call flow mechanism incorporating oneaspect of the present invention. When the GSM subscriber originates a MOshort message, the CDMA MS 320 retrieves the address of the appropriateservice center, for instance the address of GSM SMS-C 350 (FIG. 3), fromthe GSM SIM card. The address may then be encoded based on a typical GSMSMS encoding scheme. The encoded address is then embedded into a CDMAmessage as an additional part of the destination address parameter. TheMS 320 sends a CDMA message 402, typically a data burst message, to theCDMA BSS 329. The message 402 encapsulates the SMS data and containsboth address parameters (i.e., the destination address and the addressof the SMS-C). The BSS 329 may respond with a Base StationAcknowledgement Order message 404 which is sent back to the CDMA MS 320.The BSS 329 also sends a message 406, such as an ADDS Deliver message,to the to the hybrid MSC 320. The message 405 contains the SMS messageand the address parameters. The destination address parameter istransparent to the CDMA BSS 329. Therefore the present invention may beimplemented without modifying the CDMA BSS 329.

Once the message 406 reaches the Hybrid MSC 320, the hybrid MSC willremove all CDMA related headers and extract the embedded destinationaddress. Using the encoded destination address, the Hybrid MSC may thenroute the SMS message 408 to the appropriate GSM SMS-C in the CoreNetwork, for instance GSM SMS-C 350. The remaining process follows thesame procedures used in existing Short Message Service in GSM corenetworks.

In a typical mobile originated CDMA message, the destination addressparameter is one of a number of parameters sent in the message. However,as explained above, when the mobile unit is in a hybrid network wherethe CN is a GSM network, the destination address parameter includes aparameter length for both the destination address and the GSM servicecenter address. The length of the destination address is filled in theNUM_FIELDS. Thus, the GSM service center address length and the addressmay be appended to the destination address. The digits of the servicecenter address may be coded as Binary Code Decimal (“BCD”). An exampledetailed format of one embodiment of a modified destination addressparameter is illustrated as follows:

Parameter ID 1 Byte Parameter Length 1 Byte DIGIT_MODE 1 BIT NUMBER_MODE1 BIT NUMBER_TYPE 0 or 3 bits NUMBER_PLAN 0 or 4 bits NUM_FIELDS 8 BITSCHARi (note: called MS DN) (multiple occurrences) 4 or 8 bits Reserved(note: byte boundary alignment) 0 to 7 bits SMS-C address length (inunit of BYTE) 1 Byte EXT = 1 1 bit Nature of Address 3 bits NumberingPlan 4 bits BCD_2 (4 bits) BCD_1 (4 bits) 1 Byte . . . . . . . . . 0xFif odd No digits; otherwise BCD_(2i+1) (4 bits) 1 Byte the last digit

The above parameter, therefore, may be inserted into the CDMA SMSmessage as discussed above.

As those skilled in the art recognize, this disclosure providesexamples, for implementing the present invention. These specificexamples, and processes are described to help clarify the disclosure.These are, of course, merely examples and are not intended to limit thedisclosure from that described in the claims. For instance, although ageneral switching system is used to describe the HMSC, the presentdisclosure applies to any switching system that may include one or morenetwork entities which have various call control systems. Such aswitching system may serve one or more RANs of different technologies aswell as RANs sharing the same technology. The switching system may alsolink the RANs of various technologies to a CN of a predeterminedwireless technology. For instance, a soft switch technology can be usedto implement the HMSC which may include two parts each implemented in anindependent network entity. One of the two network entities may handlethe control part of a call and the other network entity may handle thebearer part. Using soft switch technology to implement the HMSC, thepresent disclosure provides a maximum leverage of equipment investmentsince the network configuration becomes highly scalable.

The example embodiments discussed above provide an economical method andsystem for sending an SMS message from the mobile to the GSM SMS-C in aGSM Core Network by passing addresses of the Hybrid MSC and the GSMSMS-C over the CDMA Radio network. The CDMA SMS protocol is modified,but the embodiment can be implemented without any modifications to anyentity between the HMSC and the mobile. Thus, the example embodimentdoes not introduce modifications to existing architectures in the RANand CN. This is a advantageous for network operators or serviceproviders because there is no need to invest in upgrading existingequipment in the RAN and CN. The illustrative embodiments can bedeployed at relatively low cost and in short deployment times becausethe core network does not have to be modified.

It will also be understood by those skilled in the art that one or more(including all) of the elements/steps of the present disclosure may beimplemented using software and hardware to develop the SMS messagecreation process at the mobile unit and to develop the messageprocessing and routing mechanism at HMSC.

Furthermore, while the disclosure has been particularly shown anddescribed with reference to the preferred embodiment thereof, it will beunderstood by those skilled in the art that various changes in form anddetail may be made therein without departing from the spirit and scopeof the disclosure, as set forth in the following claims.

1. A method to pass short message service SMS messages from a mobileunit operating in a CDMA radio access network to a global system formobile GSM SMS Center in a GSM core network, the method comprising:encoding a message into a GSM SMS encoding scheme, wherein the encodingfurther comprises encoding a destination address and an address for theGSM SMS Center into the GSM SMS message, wherein the address for the GSMSMS Center and a length of the GSM SMS Center address are appended tothe destination address; inserting the encoded message in a CDMAmessage; sending the CDMA message to a single hybrid mobile switchingcenter (MSC) in accordance with CDMA protocols, the single hybrid MSC atleast composed of a radio access network (RAN) of a first technology anda core network (CN) of a second technology, the second technology beingdifferent that the first technology of the RAN, the CN operable tocommunicate to both the CDMA radio access network and a GSM radio accessnetwork through the single hybrid MSC; receiving the CDMA message at thehybrid MSC; removing the CDMA header information to retrieve the encodedmessage by the hybrid MSC; retrieving an address for the GSM SMS Centerfrom the encoded message; and sending the SMS message to the GSM SMSCenter using the retrieved address in accordance with GSM protocols. 2.The method of claim 1 wherein the inserting further comprises embeddingthe message into the CDMA message as am additional part of a destinationaddress parameter.
 3. The method of claim 1 wherein the sending the CDMAmessage further comprises sending a data burst message to a Base StationSystem.
 4. The method of claim 1 wherein the encoding the messagefurther includes appending the CDMA destination address with the addressof the hybrid MSC.
 5. The method of claim 4 wherein the address of thehybrid MSC is coded in a Binary Code Decimal format.
 6. Atelecommunications system comprising: a CDMA radio access network; aglobal system for mobile GSM care network in communication with the CDMAradio access network; a single hybrid mobile switching center (hybridMSC) in communication with both the CDMA radio access network and theGSM core network, such that communications between the CDMA radio accessnetwork and the GSM core network are routed through the hybrid MSC,wherein the hybrid MSC contains logic for: receiving a CDMA message inaccordance with CDMA protocols, wherein the CDMA message contains anencoding GSM message containing a destination address and an address fora GSM short message service SMS Center, wherein the address for the GSMSMS Center and a length of the GSM SMS Center address are appended tothe destination address; removing CDMA header information to retrievethe encoded GSM message; retrieving the address for the GSM SMS Centerfrom the encoded message; and sending the SMS message to the GSM SMSCenter using the retrieved address in accordance with GSM protocols. 7.The telecommunications system of claim 6 wherein the retrieving theaddress further includes retrieving the address of the hybrid MSC wherethe address of the hybrid MSC is coded in a Binary Code Decimal format.8. A method to pass short message service SMS messages from a mobileunit operating in a CDMA radio access network to a global system formobile GSM SMS Center in a GSM core network, the method comprising:receiving a CDMA message at a hybrid mobile switching center (MSC) inaccordance with CDMA protocols, wherein the CDMA message contains anencoding GSM message containing a destination address and an address forthe GSM SMS Center, the single hybrid MSC at least composed of a radioaccess network (RAN) of a first technology and a core network (CN) of asecond technology, the second technology being different that the firsttechnology of the RAN, the CN operable to communicate to both the CDMAradio access network and a GSM radio access network through the singlehybrid MSC, wherein the address for the GSM SMS Center and a length ofthe GSM SMS Center address are appended to the destination address;removing CDMA header information to retrieve the encoded GSM message;retrieving the address for the GSM SMS Center from the encoded message;and sending the SMS message to the GSM SMS Center using the retrievedaddress in accordance with GSM protocols.
 9. The method of claim 8wherein the retrieving the address further includes retrieving theaddress of the hybrid MSC where the address of the hybrid MSC is codedin a Binary Code Decimal Format.